Find Search

Other Information

Quest Vitamins LTD,
8 Venture Way,
Aston Science Park,
B7 4AP.

Tel: 0121 359 0056
Fax: 0121 359 0313
Registered in England No. 2530437

Issue 87

The benefits of GLA

Why Are Essential Fatty Acids Called Essential?


Plant seed oils contain different proportions of the essential fatty acids (EFAs)
including omega 6. EFAs are polyunsaturated fats necessary for human health
because they are involved in the function and stability of all cell membranes,
in particular helping to maintain the health of the skin and its permeability
to water. They are a useful source of energy and they are needed in the production
of prostaglandins, prostacyclins and other factors collectively known as eicosanoids.

Omega 6 is rich in linoleic acid which can be converted by the body into gammalinolenic
acid (GLA). GLA is an important intermediary in the metabolic conversion of
linoleic acid to the prostaglandin E1, a substance with hormone-like activity.
Essentially the pathway goes as follows: Linoleic acid (LA) is converted into
GLA, which is converted into dihomo-gammalinolenic acid (DHGLA), which in turn
is converted into the final substance, prostaglandin E1 (PGE1). These prostaglandins
in turn lead to prostacyclins which are some of the most powerful known inhibitors
of platelet aggregation; they also relax arterial walls and promote a lowering
of blood pressure (1).

To enable all of this to happen, the body produces delta-6-desaturase, however,
for various reasons some individuals do not produce enough of this enzyme. Poor
nutrition, excess alcohol, certain types of medication, stress, excess sugar
or too much red meat in the diet all contribute to inefficient conversion of
linoleic acid into GLA and GLA to PGE1. Evening primrose oil is rich in omega
6 and, more importantly, is a source of naturally occurring GLA; borage, blackcurrant
seed, hemp and spirulina are others. However, the triglyceride patterns of all
vary slightly with the GLA from evening primrose proving most effective. GLA
is converted by the body to the hormone-like, anti-inflammatory prostaglandin
E1 providing the relevant nutrients and enzymes are present.

Evening primrose (oenotherae) is a member of the rosebay willow herb family.
Its common name is derived from its primrose yellow flowers opening mainly in
the evening. When ripe, just before the seedpods burst, the seeds from the flowers
of the plant are harvested and cold-pressed to release the oil.

The diet normally contains adequate linoleic acid derived largely through vegetable
oils. However, the first step (LA to GLA) in its conversion to prostaglandin
E1 can be easily blocked. Among the known blocking agents are: viruses, carcinogens,
cholesterol, saturated fatty acids, trans fatty acids, alcohol, insufficient
insulin, excess dietary alpha-linolenic acid (found in linseed and blackcurrant
oils), radiation, and the ageing process. A source of pure GLA obtained from
the diet can therefore be extremely valuable since it skips these potential
blockages. The body can only make prostaglandins from the essential polyunsaturated
fatty acids if the necessary vitamins, minerals and enzymes are present.

The benefits of GLA

Various nutrients are required for the different steps of prostaglandin production.
Zinc, magnesium, biotin and vitamin B6 are needed for the first step of the
process, the conversion of LA to GLA. Selenium, vitamin C, niacin and zinc are
needed for the subsequent conversion of GLA into prostaglandin E1 which can
benefit the immune system, circulation and the menstrual cycle.

Blood pressure:

Studies have shown that GLA from evening primrose oil significantly reduces
blood pressure and may also inhibit the development of hypertension (2).

Diabetic neuropathy:

Evening primrose oil may be effective treatment for diabetic neuropathy, which
involves pain and/or numbness due to nerve damage (3).

Dry eye syndrome (with inflammation):

Research has been carried out to evaluate the effectiveness and anti-inflammatory
activity of LA and GLA in the eyes of patients with dry eye syndrome. It was
found that therapy with LA and GLA and artificial tears reduced inflammation
on the surface of the eye and improved dry eye symptoms. Long-term studies have
been proposed (4).

Heart and cholesterol:

Evening primrose oil has been shown to lower high serum cholesterol levels (Ref:
Lipids, 1997,32;10:1069-1074). Dietary supplementation with evening primrose
oil has also been shown to reduce platelet aggregation (blood clotting) in those
fed a normal or high fat diet (5).

Multiple sclerosis:

Evening primrose oil is routinely used by multiple sclerosis sufferers (6).
The unusual pattern of fatty acids found in MS sufferers may return to normal
within a few months of taking EPO.

Pre-menstrual syndrome (PMS):

EPO has been used with successful results in women with PMS. This problem may
be linked with a minor abnormality of essential fatty acid metabolism resulting
in an inefficient conversion of fatty acids to prostaglandin E1 (PGE1). Evidence
shows that prostaglandin E1 is able to reduce the biological actions of prolactin,
an agent responsible for some PMS symptoms (7). However, not all studies support
these results (8).

In another study, the symptoms of swollen abdomen and breast discomfort were
eradicated in 95% of the women who took part; irritability in 80%, depression
in 74%, swollen fingers and ankles in 79% and anxiety in 53%. The only two symptoms
that persisted in more than half of the women were tiredness and headaches (9).

Rheumatoid arthritis:

49 patients, all long-standing sufferers of arthritis and taking non-steroidal
anti-inflammatory (NSAID) drugs, were given either evening primrose oil or evening
primrose oil plus fish oils. 60% of the patients were able to withdraw completely
from NSAID treatment, and another 25% were able to cut their NSAID dosage in
half. Evening primrose oil with Fish Oils was slightly more effective than EPO
alone (10).

Skin conditions:

Research into EFA metabolism and its modification in atopic eczema is well documented,
with many studies carried out in the later half of the last century.

Low blood EFAs have been evident in the common inherited skin condition atopic
eczema. There has also been evidence of a good response to high doses of linoleic
acid, although more current research shows that while linoleic acid levels are
quite high in the blood, and adipose tissue of patients with atopic eczema,
the metabolites of linoleic acid (GLA being one) are not as high as they should
be. The administration of GLA had generally been found to improve the skin condition.
Atopic eczema may be caused by a minor inherited abnormality of EFA (11).

Evening primrose oil has been used successfully in patients with atopic eczema.
A double blind cross-over study was used with adults taking either 4, 8 or 12
x 500mg capsules daily and children taking 4 or 8 x 500mg capsules daily. Results
indicated that evening primrose oil brought significant clinical improvement
to dermatitis, especially at the higher intakes (12).

Evening primrose oil has been used effectively for many purposes. It may be
taken in capsule or in liquid oil form. For best effect the GLA content should
be typically a minimum of 10%. However, it should be borne in mind that the
delicate nature of the oil lends itself to being oxidized very quickly on exposure
to oxygen, therefore capsules provide a fresh measure each time. Evening primrose
oil can be used without harm at levels of up to 5-6g daily*.

* High amounts of evening primrose oil should be avoided by epileptics as it
may exacerbate a certain type of temporal lobe epilepsy. Also, evening primrose
oil is best not taken with drugs for schizophrenia. Occasionally, evening primrose
oil may cause nausea, headaches or skin eruptions when first taken. Symptoms
can be lessened by taking with a meal.

Why Are Essential Fatty Acids Called Essential?

Essential fats are so called because they are essential for life. They cannot
be synthesized in the body and must be obtained through plant and fish oils
in the diet, there are no short-cuts! There are two types of essential fat,
omega 3 and omega 6. Essential fatty acids are polyunsaturated fats that are
good for our health in moderation. Approximately 6% of total energy intake should
come from polyunsaturated fats.

Non-essential fats are saturated fats, hydrogenated fats, lard, commercial cooking
oil, shortening used in pastries, biscuits; most margarines and spreads and
so on. No more than 10% of total energy intake should come from saturated fats.
Too much saturated fat, trans-fat, or hydrogenated fat spoils the real benefit
of polyunsaturated fat in the body by blocking the PUFA receptor sites.

Consider for a moment all the sneakily eaten confectionery bars, biscuits and
chips and the long-term damage of the effects on the body!


1. "Human Nutrition & Dietetics", Garrow, James and Ralph. Churchill
Livingstone. 2000.

2. Prostaglandins Leukot Essent Fatty Acids, 1993,49;4:809-814.

3. Keen H, Payan J, Allawi J, et al. Treatment of diabetic neuropathy with gamma-linolenic
acid. The Gamma-Linolenic Acid Multicenter Trial Group. Diabet Care 16: 8-15,

4. Cornea. 2003 Mar;22(2):97-101.

5. Annales de la Nutrition et de lAlimentation, 1980,34;2:277-290.

6. The Lancet, 1997,350;9092:1685.

7. "Primrose oil in the treatment of Pre-menstrual syndrome", B Larsson
& S Fianu, Dept. Obstetrics and Gynaecology, Hudding University Hospital,
Sweden, 1986.

8. J Obstetrics and Gynaecology, 1993,81;1:93-98.

9. Current Therapeutic Research, 1989, 46;1:58-63.

10. Annals of the Rheumatic Diseases, 1988,47:96-104.

11. Am J Clin Nutr. 2000 Jan;71(1 Suppl):367S-72S.

12. Ref: The J Int Medical Res, 1994;22:24-32).

Print this page